content: /*
   * Copyright 2016-present David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.rxjava3.basetypes;
  
  import org.reactivestreams.Subscriber;
  
  import io.reactivex.rxjava3.functions.Predicate;
  import io.reactivex.rxjava3.internal.subscribers.BasicFuseableSubscriber;
  
  /**
   * Filter the upstream value with a predicate.
   *
   * @param <T> the value type
   */
  final class PerhapsFilter<T> extends Perhaps<T> {
  
      final Perhaps<T> source;
  
      final Predicate<? super T> predicate;
  
      PerhapsFilter(Perhaps<T> source, Predicate<? super T> predicate) {
          this.source = source;
          this.predicate = predicate;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> s) {
          source.subscribe(new FilterSubscriber<T>(s, predicate));
      }
  
      static final class FilterSubscriber<T> extends BasicFuseableSubscriber<T, T> {
  
          final Predicate<? super T> predicate;
  
          FilterSubscriber(Subscriber<? super T> downstream, Predicate<? super T> predicate) {
              super(downstream);
              this.predicate = predicate;
          }
  
          @Override
          public void onNext(T t) {
              if (sourceMode == NONE) {
                  boolean b;
                  try {
                      b = predicate.test(t);
                  } catch (Throwable ex) {
                      fail(ex);
                      return;
                  }
                  if (!b) {
                      return;
                  }
              }
              downstream.onNext(t);
          }
  
          @Override
          public int requestFusion(int mode) {
              return transitiveBoundaryFusion(mode);
          }
  
          @Override
          public T poll() throws Throwable {
              T v = qs.poll();
  
              return v == null || predicate.test(v) ? v : null;
          }
      }
  }
  